Granular Activated Carbon (GAC) Contactors

Granular activated carbon (GAC) absorption is commonly used for the advanced (tertiary) treatment of municipal and industrial wastewater. GAC is used to adsorb small quantities of soluble organics and inorganic compounds such as nitrogen, sulfides and heavy metals remaining in the wastewater following biological or physical-chemical treatment. Adsorption occurs when molecules adhere to the internal walls of pores in carbon particles produced by thermal activation.

With the promulgation of the US EPA Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 D/DBP Rule), water utilities are now faced with more stringent requirements concerning the concentrations of total trihalomethanes (TTHMs) and five haloacetic acids (HAA5). Installing Wigen's GAC contactor technology is a proven approach to lowering the levels of these contaminants by removing organic precursors. This mode of treatment is gaining popularity as utilities become aware of the potential unintended consequences associated with converting secondary disinfection from free chlorine to chloramines.